Henry Quantum has several thoughts going through his head at any given time, so it's no surprise when he forgets something very important -- a Christmas gift for his wife, Margaret, which he realises on the morning of December 23rd. So Henry sets off in search of the perfect present for Margaret: a bottle of Chanel No. 5. But much like Henry's ever-wandering mind, his quest takes him in different and unexpected directions, including running into the former love of his life, Daisy. Meanwhile, Margaret is questioning whether she and Henry belong together after all ... The Heart of Henry Quantumis a sweet, funny, and touching debut which shows how the seemingly insignificant events of one single day can change our lives forever -- perhaps, if we're lucky, for the better.